Carburetor



S. L. PICARD Aug. 25, 1931.

CARBURETOR Filed Feb.

lll/MII] INVENTOR ATTORNEYS Patented' Aug. 25,1931 l PATENT OFFICE SIDNEY L. PICARD, OF DETROIT, MICHIGAN CARBURETOR.

Application led February 5, r1930. Serial No. 425,925.

This invention relates to a carburetor for supplying combustible mixtures of air and yliquid fuel to the cylinder of an internal combustion engine, and an object of the present construction is to automatically proportion the amount of fuel to air for all power and speed requirements of the engine, giving a rich mixture at low speeds and high power requirements and proportionally less fuel to air at higher engine speeds throughout the entire range, thus effecting a saving in fuel consumption.

A further object is to provide auxiliary fuel and air supplying means for supplying small quantities of combustible mixture to the engine when thethrottle is fully closed, which supply will be suflicient tokeep the engine running at its lowest speed` and when no power is otherwise required,.thus obviating the stalling of the engine by the closing of the throttle. y v

With the above and other ends in view, the invention consists in the construction, arrangement and combination of elem-ents, all as hereinafter set forth and more particularly pointed out in the appended claims, reference being had to the accompanying drawings in which- Figure 1 is a longitudinal vertical section through a device illustrative of an embodiment of the present .invention and showing the float chamber thereof substantially in side elevation; and v v Fig. 2 is a cross-sectional detailsubstantially upon the line 2-2 of Figure l.

As shown in the drawings, the carburetor comprises the usual body l of any desired form or` size, providing an air inlet tube 2 in'which is located the usual choke valve 3 and from the inner endkof this tubular passage 2 rises a vertical passage 4 of approximately the same diameter as said passage 2 and forms t-he lower end portion of an outlet tubular passage 5 to the upper end of which the usual intake manifold (not shown) leading to the engine cylinders is adapted to be secured in the usual manner, said outlet 5 being preferably formed as a part of a capV indicated as a whole by the numeral 6, for the carburetor, said cap forming a cover for closlower lend of this vtapered end of thev nozzle ing the upper end of a float chamber-7 formed integral wtih the body 1 and secured in place thereover by screw bolts 8 in the usual manner. Gasoline is supplied to the float chamber through the usual connection 9 on the cap to which connection a pipe line (not shown) is connected and a level of such fuel is maintained in the floatchamber by means of the usual valve and float (not shown).

At the lower end of the passage 4, between it and the inner end of the air inlet passage 2, an inwardly extending annular ledge 10 is provided which forms a seat for an air valve 11 having a tubular stem l2 which stem is guided in a guide bearing 13 supported by or formed integral with a bridge 14 extending transversely of the i'nner end of the passage 2, said guide bearing being bored inwardly from its lower end to form a chamber 15 for a coiled spring 1G which seats, at its upper end against the inner end of said chamber 15 and at its lower end within a cupped nut 17 screwed upon the Screw-threaded exterior of a Venturi plug 18 which in turn is screwed into the lower end of the tubular stem 12. The interior of the plug 18 is bored to provide a Venturi restriction, that is, its bore tapers inwardly from each end of the plug, forming a restriction 19 intermediate the ends of the bore, the small ends of these tapered portions of the bore meeting intermediate vthe ends of the plug at 19. The taper of the bore at the plug is substantially the same as the taper of the upper end portion of a nozzle 'member 20 which is screwed into an opening in the bottom wall of the .body 1 a-t the lower side of the passage 2,

and which nozzle is adapted to project into this tapered end portion of the bore of the plug, the parts being so proportioned and adjusted that when the valve '11 is seated, thus limiting the downward movement of the plug," there will be a very narrow annular passage 21 between the exterior of the and the tapered bore in the plug for the' passage of air upwardly around the nozzle and through the tubular stem' 12 into the passage 5 leading to the engine. The size of this passage 21 may be readily varied by screwing said plug in or out within the stem.

The nozzle 20 is provided with a small axial bore 22 for the passage of gasoline or fuel oil upwardly therethrough from a chamber 23 at the lower end of the nozzle, which chamber is constantly supplied with oil through a passage or duct 24 leading thereto from the bottom of the float chamber 7, the flow of oil through said nozzle being regulated by a needle valve 25 extending f across the chamber, the stem 26 of which valve is screwthreaded to engagea screwthreaded opening in a' boss formed on the lower side of the body and provided with a. packing gland 27, in the usual manner, to prevent leakage around the stem. As the nozzle is therefore always in direct communication with the iloat chamber, a `level of oil ismaintained at a certain height within the nozzle,dependent upon the level of oil in the float chamber which is maintained by the float therein` in the usual manner.

At low engine speeds, the partialvacuum created in the passage 5 by engine inspiration, will draw air through the tubular valve stem and through the space 21 around the nozzle, this flow of air picking up fuel from the open end ofthe nozzle which projects slightly beyond the Venturi restriction 19 where the airv expands as it rushes therethrough and completely vaporizes the fuel, forming rich explosive charges for low engine speeds and high power. As the speed of the engine increases, increasing the suction acting upon the air valve 11, this valve will lift from its seat, permitting additional air to pass into the outlet 5 for admixturev with the charges being drawn through the tubular stem of this valve, and as said air valve is thus lifted against the resistance of the spring 16, 'the Venturi plug 18 will also be lifted, bringing its restriction 19 nearer the outlet end of the nozzle 18 and thus increasing the air space-21 and volume of air flowing therethrough and also the action of this air flow upon the nozzle outlet to increase. the fiow of fuel therefrom in proportion to engine speed. At high engine speeds, the air valve 11 will be lifted from its seat to the limit of its upward movement permitted by the spring 16 and length of bore 15 into which the nut 17 moves, thus greatly increasing the size of the air passage 21 around the nozzle and the flow of air therethrough, the Venturi restriction 19 being thus moved to a position adjacent to or above the discharge end ofthe nozzle. y

The flow of fuel and volume of air is thus automatically proportioned according to the varying engine speeds I to give the correct mixture at all speeds from' the lowest to the highest and a rich mixture for starting, and

by adjusting the Venturi plug within the charges to the engine and consequent stalling of the engine by the complete closing of said valve, passages 29 and'30 are formed in the body 1 beyond the end of the air inlet passage 2, said passage 29 opening at its lower end into the fuel passage 24 and its upper end opening into the bottom of a small mixing chamber 31,l the passage 30 being in open communication at its lower end with the main air inlet passage 2 and its upper end opening directly into the bottom of said mixing chamber, which mixing chamber is in open communication with the main outlet 5 above the throttle 28, through a passage-32.

therethrough for the escape of fuel from said passage into said chamber under the influence of a partial vacuum created in said chamber by engine operation when the throttle 28 is fully closed, lthis vacuum in said chamber also causing air to flow into the chamber for admixture with said fuel, through the passage 30. In order that the proportion of air to fuel may be properly adjusted and regulated, a valve 34 is provided in the passage 30, said valve rcomprising a rod 35 secured within a bore in the body 1, which bore intersects the passage 30, and which rod is formed with a notch or cutaway side extending across the passage so, that by turning the rod, the passage may be blocked to the .desired extent by the partially cut away end portion of the rod. The outer screwthreaded to receive a plug 36 for locking the valve rod in adjusted position.

An auxiliary supply of combustible mixture is thus provided for supplying the engine when idling with the throttle fully closed, this supply being suiiicient for idling speeds where little power is required, and the mixture thus supplied contains just sufficient fuel ingredient to form a combustible mixture. Starting of the engine by closing the throttle, in bringing the vehicle to a stop, is thus prevented as suiiicient charges are supplied regardless of the position of the throttle, to keep the engine running.

Obviously changes may be made in the specific construction and arrangement of parts, within the scope of the appended claims, without departing from the spirit of the invention, and I do not, therefore, limit myself to the particular construction and arrangement shown.

Having thus fully described my invention, what I claim is f 1. In a carburetor, the combination of a of the plug and forming a Venturi restricaov tion in said bore, a spring sleeved on said stem to normally hold said Valve seated, a fuel nozzle having a tapered end portion corresponding to said taper of the bore in the lower end of said plug and projecting into said bore, and means for supplying a liquid fuel to said nozzle.

2. In a carburetor, the combination of a body having a horizontal air inlet passage and a vertical outlet passage meeting the inner end of said air inlet passage, said outlet passage being formed with an annular valve seat at its lower end, a valve to seat upon said seat and provided with a tubular stem forming a passage through said valve connecting said air inlet and said outlet passages, a fixed bridge extending across the inner end of said air inlet passage below said valve and formed with a chambered guide for said stem. a coiled spring within said chamber of said guide, a plug screwed into the and openin at itsupper end into said outjet member in the upper end of said uel supplying passage opening into said mixing chamber.

In testimony whereof I afiix my signature.

SIDNEY L. PICARD.

lower end of said stem and formed with a bore tapered inwardly from each end of said plug to form a Venturi restriction in said bore, a cupped nut upon said plug to form an adjustable seat for the lower end of said spring, a fuel nozzle secured in the lower side of said air inlet passage opposite the lower end of said plug,"said nozzle being formed with a tapered upper end to project into the lower tapered end of said plug, said plug being adapted to be screwed into and out of said stem to vary the space between said plug and nozzle, and means for supplying a liquid fuel to said nozzle.

3. In a. carburetor, the combination of a body having a horizontal air inlet passage and a Vertical outlet passage meeting the inner end of said air inlet passage, a suction operated valve controlling communication between said passages and formed with an air passage therethrough, means for supplying liquid fuel to said air passage through said valve, a throttle valve in said outlet passage beyond said suction operated valve, said body being also formed with parallel passages in its wall-opposite the end of said air inlet passage, one of said parallel passages opening at its lower end into said air inlet passage and the lower end of the other of said parallel passages being in open communication with a liquid fuel supply, said body being also formed with a mixing chamberinto which the upper ends of said parallel passages open and also formed with a passage leading from said mixing chamber let passage eyond said throttle valve, and aV 

